Window polisher

ABSTRACT

An automatic polishing machine for polishing aircraft windows uses pressurized air to create a suction to hold the polishing unit on the aircraft, creates a suction to automatically pick up a polishing pad, which is impregnated with polishing compound, and, using a motor driving through a flexible drive joint, and using X and Y axis step motors, drives a polish head along the aircraft window, polishing the window.

BACKGROUND OF THE INVENTION

This application claims priority from U.S. Provisional Application Ser.No. 60/004,114, filed Sep. 21, 1995 and is a national filing ofPCT/US96/15015, filed Sep. 18, 1996. The present invention relates towindow polishers, and, in particular, to a device which canautomatically polish aircraft windows.

Aircraft windows become scratched over a period of time, as they undergosomething similar to a sand-blasting process when the aircraft flies athigh speeds through dust-laden air. Rather than discarding the scratchedwindows, the windows are usually removed from the aircraft, arepolished, and then are put back on the aircraft with a new seal. This isa very labor-intensive, time-consuming, and expensive process. In somecases, the labor costs are so high that the windows are shipped to acountry with low labor costs and are then returned to be re-installed onthe aircraft. However, this leaves the aircraft disabled during theperiod of time that the windows are being removed, polished, andreplaced.

An attempt has been made to automate the polishing process prior to thepresent invention, so that the windows could automatically be polishedwhile they remained on the aircraft, but this attempt failed. Themachines simply did not work, for a number of reasons.

SUMMARY OF THE INVENTION

The present invention provides a machine which permits the polishingprocess to be automated, speeding up the process from approximately twohours per window to approximately ten or fifteen minutes per window. Theprocess requires very little labor and permits the aircraft to be putback into use very quickly, thereby greatly reducing the out-of-pocketcost of the polishing process and the cost due to lost use of theaircraft.

The present invention provides a machine which makes few demands interms of equipment that must be made available at the airport. Itrequires only electricity, a source of pressurized air, water to refilla water tank on the machine, and a supply of polish pad kits.

The present invention provides a polish head which automatically picksup and disposes of disposable polish pads by using a vacuum to pick upthe pad and pressurized air to blow the pad away from the polish head.

The present invention provides a polish head which is rotated and movedover the surface of the window to polish the window but which isconnected to its drive shaft by a flexible drive joint so that thepolish head can pivot as necessary to match the contours of the aircraftwindow, which is curved, not planar. This is important to the properfunctioning of the polisher.

The present invention provides special polish pads which are made up ofa plurality of segments adhered to a backing, with the polish pads beingimpregnated with polishing compound which is released when water issquirted on the window and the polish head is passed over the window.This eliminates the need for pumping various types of polishingcompounds to the machine. The segments are also spaced from each otherso that water and air can pass completely around each segment as it isoperating, thus helping to cool the window as it is being polished andto ensure good coverage of the polishing compound over the window.

The present invention provides suction feet which hold the machine ontothe side of the aircraft. By pushing a button, the operator can changefrom having pressurized air flow out of the suction feet to having asuction at the suction feet. The pressurized air helps the operatorslide the unit along the side of the aircraft to help locate it properlyover the window, and the suction holds the unit on the side of theaircraft.

There are many other advantages of a machine made in accordance with thepresent invention, as will become obvious from reading the descriptionwhich follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of an aircraft with a window polisher made inaccordance with the present invention mounted on the aircraft forpolishing the aircraft window;

FIG. 2 is a top view of the portion of the polisher mounted on thewindow in FIG. 1, looking toward the aircraft;

FIG. 3 is bottom view of the portion of the polisher of FIG. 2;

FIG. 4 is a side sectional view of one of the suction feet of thepolisher of FIG. 2;

FIG. 5 is a side sectional view of the polish head of the machine FIG.2;

FIG. 5A is a side view of the polish head of the machine of FIG. 2,showing in phantom how the polish head moves to pick up a polish pad andthen moves down to the surface of the window;

FIG. 6 is an enlarged side sectional view of the polish head of FIG. 5;

FIG. 7 is an exploded perspective view of the polish pad kit and thereceptacle which receives the polish pad kit of the machine of FIG. 1;

FIG. 8 is a side sectional view of the kit and receptacle of FIG. 7;

FIG. 9 is a bottom view of one of the polish pads of FIG. 7;

FIG. 10 is a side view partially in section of the polish head andpolish pad polishing a window;

FIG. 11 is a front view of the control unit for the polisher of FIG. 1;

FIG. 12 is a side view of the control unit of FIG. 11;

FIG. 13 is a schematic of the pneumatic system of the machine of FIG. 1;and

FIG. 14 is an electrical schematic of the machine of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows the side of an aircraft 10, having a plurality of windows12. A window polishing machine 14, made in accordance with the presentinvention, is mounted on the side of the aircraft 10 over a window 12for polishing the window 12. As shown in FIG. 1, the machine 14 includesa remote portion 16, which is wheeled around on the tarmac by a dolly18, and a hanging portion 20, which hangs on the side of the aircraft10. The hanging portion 20 may also be wheeled around on a dolly (notshown). There is a trunk line 22 extending from the remote unit 16 tothe hanging unit 20, which includes electrical lines, pressurized airlines, and a water line, as will be described later.

FIG. 2 shows more of the details of the hanging unit 20 of the polishingmachine 14. The hanging unit 20 includes a frame 24, which is made up oftwo parallel forward-to-back frame members 26 and two parallelleft-to-right frame members 28 which are connected together to form therectangular frame unit 24.

Four suction feet 30 are bolted onto the frame 24 and are directeddownwardly, toward the aircraft 10. As will be described later, thesesuction feet adhere to the side of the aircraft by means of suction inorder to hold the hanging unit 20 on the aircraft 10.

A left threaded rod 32 and a right threaded rod 34 are mounted on blocks36, which are bolted to the frame 24. The left and right threaded rods32, 34 are mounted directly over the forward-to-rear frame members 26.There is also a forward-to-rear unthreaded rod 37 on the right side ofthe frame 24. A Y-axis motor 38 is mounted on the forward right cornerof the frame 24 and drives the right screw rod 34. As shown in phantomat the back end of the right screw rod 34 is a pulley 40, which carriesa timing belt 44, which drives a left pulley 42, mounted on the end ofthe left screw rod 32, so that, as the Y-motor 38 turns the right screwrod 34, it causes the pulley 40 to rotate, which rotates the timing belt44, which rotates the left rod 32, so that both rods 32, 34 rotatetogether. The Y-motor 38 is a step motor, in which each rotation of themotor is 1,000 steps, and an electrical controller, located at theremote portion 16, tells the Y-motor 38 how many steps to rotate,thereby closely controlling the motion of the rods 32, 34.

Left and right follower blocks 46, 48 are mounted on the threaded rods32, 34, respectively, and move backward and forward on the rods 32, 34,following the threads on those rods as the rods rotate. The rightfollower block 48 is also mounted with a sliding fit over the unthreadedrod 37.

Two left-to-right rods 50, 52 are mounted between the follower blocks46, 48 and travel forward and back along the frame 24 along with thefollower blocks 46, 48. An X-motor 54 is mounted on the right followerblock 48 and also travels with the follower blocks 46, 48. The rearleft-to-right rod 50 has a threaded outer surface and is rotated by theX-motor. Again, the X-motor 54 is a step motor, the rotation of which istightly controlled by the remote unit 16.

A polish head carrier block 56 is mounted on the left-to-right rods 50,52 and moves left and right, following the threads of the threaded rod50, as it is driven by the X-motor 54. Thus, the X-motor and Y-motorcontrol the motion of the polish head carrier block 56 along a planewhich is substantially parallel to the side of the aircraft.

Also seen in FIG. 2 are a polish kit receptacle 58 and a secondreceptacle 60, which are fixed to the frame 24 at an elevation above thebottom of the suction feet 30. Also fixed to the frame 24 are threewindow locating brackets 62, which are aligned with the left, right, andtop edges of the window 12 to properly align the remote unit 16 with thewindow 12. Left and right handles 64 are fixed to the forward-to-rearframe members 26 for carrying the remote unit 20 by hand.

Several other features of the machine can be seen in FIG. 2. Thesefeatures will be described in more detail later. There is a vacuumrelease button 66 near the left handle 64. This vacuum release button 66is enclosed by a hinged cover 68. There is a water nozzle 70, and thereis a water filter 72. There is a start button 74 and a stop/reset button76. There is also a strobe light 78. The location of the polish head 110and the air motor 112 which drives the polish head 110 can also be seenin FIG. 2.

FIG. 2 also shows several limit switches, which sense when the polishhead carrier block 56 has reached the outer limits of travel. The firstlimit switch 80 is in the forward right corner of the frame 24, and itscontact 82 is on the polish head carrier block 56. The second limitswitch 84 is on the right follower block 48, and its contact 86 is inthe right rear corner of the frame. The third limit switch 88 is locatedon the forward left corner of the polish head carrier block 56, and itscontact 90 is on the frame near the left handle 64. The fourth limitswitch 92 cannot be seen in this view, but it lies directly below thecontact 82 for the first limit switch 80. The contact 94 for the fourthlimit switch 92 is on the frame near the right handle 64.

Also shown in FIG. 2 are the lines which are enclosed in the trunk line22, extending from the remote unit 16 to the hanging unit 20. These area water line 96, a pressurized air line 98 to control the up-and-downmovement of the polish head 110, a pressurized air line 100 to drive theair motor 112 which rotates the polish head 110, a pressurized air line102 which goes to the suction feet 30 and the polish head 110, anelectrical line 104, which controls the X-motor 54, an electricalcontrol signal line 106, which controls the solenoid valves on thehanging unit 20, and an electrical line 108, which controls the Y-motor38.

FIG. 3 shows a bottom view of the hanging unit 20. In addition toshowing many of the parts that are seen in FIG. 2, FIG. 3 shows thebottom side of the suction feet 30, it shows the polish head 110 and theair motor 112 which drives the polish head 110. Also, in FIG. 3 areshown three venturi valves 114, 116, 118, which are solenoid valveswhich, in a first position, allow pressurized air to pass through, and,in a second position, use a venturi effect to create a suction from thepressurized air. Two of the venturi valves 114, 116 are used to create asuction or to provide pressurized air at the suction feet 30. The thirdventuri valve 118 provides suction or pressurized air at the polish head110.

FIG. 4 is a detailed view of the left front suction foot 30. The othersuction feet 30 are identical to this foot, except that they are mountedon different parts of the frame 24 and may have different air linesextending to them.

The left front suction foot 30 includes a hollow shaft 120, which slidesup and down inside of an upper sleeve 121 as shown by the arrow 123. Theupper sleeve 121 has threads 122 at its top end, which are threaded intoa nut 124, which is bolted to the underside of the left frame 26. Theshaft 120 is stopped in its upward travel by the nut 124, and it isstopped in its downward travel by the sleeve 121, because the interiorof the sleeve 121 has a reduced diameter portion beyond which theenlarged diameter upper portion of the foot shaft 120 cannot pass. Anair line 126 is connected to the nut 124, and communicates with theinterior of the shaft 120.

A lower sleeve 127 is fixed to the bottom portion of the foot shaft 120,and a spring 130 extends between the upper sleeve 121 and the lowersleeve 127 and serves as a shock absorber. The outer surface of thelower sleeve 127 is threaded, and a connector 132 is threaded onto thelower sleeve 127. The connector 132 is fixed to the upper portion 134 ofa ball joint, and the lower portion 136 of the ball joint is threadedonto a foot 138. A flexible suction cup 140 is mounted onto the foot138. There is a fluid path through the center of the foot shaft 120,through the upper and lower portions 134, 136 of the ball joint, throughthe foot 138, and through the soft cup 140, which permits air to flowthrough. There is a soft, flexible cover 142 over the ball joint parts134, 136 to protect the joint.

If pressurized air passes through the air line 126 to the soft cup 140,then the suction foot 30 is provided with a layer of air, which helps itglide smoothly over the surface of the aircraft 10 to help locate itproperly over the window 12. If a vacuum is drawn through the air line126, then it pulls a suction from the soft cup 140, which provides thepressure differential needed to hold the hanging portion 20 of themachine 14 on the aircraft 10. Actually, the embodiment shown here canbe held on the aircraft 10 if only one of the four suction feet 30 isworking properly.

FIG. 5 shows the polish head 110, which is supported on the polish headcarrier block 56 described earlier. A cylinder 144 is fixed to thepolish head support block 56. A piston 146 fits inside the cylinder 144and travels up and down in the cylinder 144, depending upon thepressures in the chambers above and below the piston 146. The upperchamber is vented to atmosphere through the vent 150, and the lowerchamber is connected to an air line 98. The piston 146 includes atubular bracket 146A, and inside the tubular bracket 146A is the polishhead shaft 152. The tubular bracket 146A and the polish head shaft 152travel up and down relative to the carrier block 56 as the piston 146travels up and down in its cylinder 144.

The top of the tubular bracket 146A is threaded onto a cylindricalbracket 154, which slides up and down in a vertical, cylindrical hole156 of the block 56. The cylindrical bracket 154 has an enlarged topportion, which includes a recess 158 into which is pressed a bearing160, which supports the polish head shaft 152. The flat top surface ofthe cylindrical bracket 154 is fastened to a motor support 162, whichsupports the air motor 112. The motor support 162 also supports thepulleys 164, 166 and the drive belt 168, through which the air motor 112drives the polish head shaft 152. An air line 170 is connected to thetop of the hollow polish head shaft 152 through a connector 172, whichallows the shaft 152 to rotate while the air line 170 remainsstationary, still maintaining an open conduit from the air line 170,through the shaft 152.

There is also an air line 100 to the air motor 112, and there are twovents 174 from the air motor 112.

The lower portion of the piston bracket 146A is enlarged and houses asecond bearing 160, which supports the lower end of the polish headshaft 152. There is also a spring 176, located between the cylinder 144and the enlarged portion of the piston bracket 146A. This spring 176provides the force which pushes the polish head 110 down, to polish theaircraft window 12.

The bottom of the polish head shaft 152 is threaded onto the top portion178 of a ball joint, and the bottom portion 180 of the ball joint isthreaded onto the polish head 110. There is also a piece of flexiblehose 182 which is fastened on top to the top 178 of the ball joint andis fastened on the bottom to the bottom 180 of the ball joint. This hose182 provides a flexible drive between the top and the bottom of the balljoint, so that the resulting joint provides a flexible drive joint,which drives the polish head 110, allows the polish head 110 to pivot inall directions, and provides an air passage from the drive shaft 152through the polish head 110. Phantom lines show some of the directionsin which the polish head 110 can pivot about the flexible drive joint,while still being rotated by the drive shaft 152 and still permittingair flow through the joint.

The polish head 110 includes a rigid back portion 184 onto which isconnected a flexible rim 186. Located across the inside diameter of theflexible rim 186 is a porous plate 188. This porous plate 188 ispreferably made of a man-made rock with pores in it, so that the airpressure or the vacuum from the air line 170 reaches the outer face ofthe plate 188 in order to hold the polish pad on the polish head 110 orto blow the polish pad off the polish head.

FIG. 5A shows the same polish head 110 as FIG. 5, except, in this view,the piston 146 has moved upwardly in the cylinder 144, due to airpressure in the line 98. This retracts the polish head 110 so the polishhead 110 can move over the polish pad kit 190 to pick up a polish pad(shown in later figures). In order to move the polish head 110 over thekit 190, the X-motor 54 and the Y-motor 38 rotate their respectiveshafts, moving the polish head carrier block 56 directly over the kit190. Then, the air pressure in the line 98 is released, thereby loweringthe polish head 110 down into the kit 190 to pick up the polish pad.Then, the line 98 is again pressurized, retracting the polish head 110,and then the X-motor 54 and the Y-motor 38 drive the polish head 110back over the window. The air pressure in the line 98 is again reduced,extending the polish head 110 to the position shown in phantom in FIG.5A, where it is pressed against the window 12 by the spring 176.

FIG. 6 is an enlarged view of the bottom portion of FIG. 5, showing thepolish head 110 and the flexible drive joint.

FIGS. 7 and 8 show the polish kit receptacle 58, the polish kit 190, andthe sensor 192, which senses whether there is a polish kit 190 in thereceptacle 58. The polish kit receptacle 58 has opposed slots 194, andthe kit 190 has opposed ears 195, which are received in the slots 194 tohold the kit 190 in the receptacle 58. To put a kit 190 into areceptacle 58, the opposed ears 195 must be aligned with the topopenings of their respective slots 194, and then the kit 190 is pusheddown and twisted clockwise or counterclockwise, drawing the kit 190 downinto the receptacle 58, and retaining it in place. When the kit 190 isin position, the sensor 192 senses its presence in the receptacle 58.

In each kit 190 are at least two polish pads 196, 198. Each polish pad198 has a circular, flat, solid back member 199 and a plurality of padsegments 200, which are adhered to the face of the back member 199 withspaces between the pad segments 200 to permit water and air to passbetween the pad segments 200. The pad segments 200 are preferably madefrom "Finesse-It Buffing Pad" material, which is sold by 3MInternational. The upper pad 196 is actually the finishing pad, whichwill be used last, and the lower pad 198 is the pad which will be usedfirst. The lower pad 198 has been impregnated with a rubbing compoundwhich has been allowed to dry. This compound is preferably ERR-Bee 103fine white, which is manufactured by AB ERR-BEE in Sweden. The upper pad196 has been impregnated with a finer, finishing compound which has beenallowed to dry. The finishing compound is preferably 3M Finesse-It09639, sold by 3M International. The backing plate 199 may be made of ametal disk or a cardboard disk. The kits 190 will be provided to thecustomer in a sealed condition to be sure that the polish and finishingcompounds retain their properties until the polish pads are used. Whenwater is squirted onto the aircraft window and the polish pads 196, 198move over the surface of the window, the polish compound and finishcompounds are dissolved, making them available for use in automaticallypolishing the window.

FIG. 10 shows the polish head 110 with a polish pad 196 in place on theface of the polish head 110 and pressing against a window. It can beseen here that the outside diameter of the polish pad 196 isapproximately the same as the outside diameter of the flexible rim 186.The vacuum in the line 170 pulls a vacuum through the porous plate 188,and causes the pad 196 to adhere to the polish head 110 as the polishhead 110 rotates and travels along the surface of the window.

FIGS. 11 and 12 show the remote unit 16. The remote unit 16 is carriedon a dolly 18. Inside the remote unit 16 is a computer (not shown),which controls the operation of the machine 14. There is a window 210 onthe front of the remote unit 16, through which a display can be seen,and there are touch pads 212, which allow an operator to control thecomputer. The remote unit 16 carries a water tank 214, and it carries anumber of valves, which will be described in detail later. On the frontof the remote unit 16 are an on/off switch 216 and an indicator light218 for the power supply. The power supply cord 220 is shown. There is alock 222, which locks the remote unit 16 closed, keeping people out ofthe inside of the box.

Pressurized air is usually available at an airport, and the pressurizedair line is just connected to the air inlet 224 of the remote unit 16.There is a manual valve 226, for turning the air on and off manually atthe remote unit 16, and there is a pressure switch 228, which senseswhether there is sufficient air pressure at the machine and which shutsthe machine down if there is not sufficient air pressure. Above thewater tank 214, and not shown in these drawings, are an emergency stopbutton, an alarm, and a water filter, to filter water leaving the watertank 214.

FIG. 13 shows a schematic view of the pressurized air system. Thepressurized air inlet 224 to the remote unit 16, the manual valve 226,drain 227, pressure switch 228 and pressure regulator 229 are shown atthe top left of the schematic diagram. The three air lines in the trunkline 22 going from the remote unit 16 to the hanging unit 20, which areshown in FIG. 2, are reflected in this diagram. They are the pressurizedair line 98, which goes to the polish head cylinder 144 to raise andlower the polish head 110; the pressurized air line 100, which goes tothe air motor 112, which drives the polish head drive shaft 152; and thepressurized air line 102, which communicates with the suction feet 30and the polish head 110.

The solenoid valve 230 in the line 100 to the air motor 112 and thevalve 232 in the line 98 to the cylinder 144 are located in the remoteunit 16. There are also solenoid valves 234 and 234A-C in the air lines126 and 126A-C to the suction feet 30. These solenoid valves 234 arelocated on the hanging unit 20 and are controlled by the centralprocessor at the remote unit 16. These valves are biased in the closedposition, so they will close if a signal is lost from the centralprocessor. If there is a suction in the lines 126 and the valves 234 areclosed, they will hold the suction in the suction feet 30 for a longperiod of time, even if there is a problem with the air pressure linesto the machine. This gives the operator plenty of time to take down thehanging unit 20 or remedy the problem well before the hanging unit 20falls off of the aircraft.

The venturi valves 114, 116, and 118 were referred to earlier. They arelocated on the hanging unit 20 and control whether pressurized air or avacuum goes to the end point. The valve 114 controls the air lines 126and 126A to the left suction feet 30, and the valve 116 controls the airlines 126B and 126C to the right suction feet 30. The valve 118 controlsthe air line 170 to the polish head 110. Each of these venturi valves114, 116, 118 is shown schematically as being made up of severalparts--a first valve 236, a second valve 238, a venturi 240, a vent toatmosphere 242, a first path 244, and a second path 246.

If both the first valve 236 and the second valve 238 are closed, thennothing goes to the end point--neither pressurized air nor a vacuum. Ifthe first valve 236 is open and the second valve 238 is closed, thenpressurized air goes through the path 246 to the end point, providingpressurized air to the feet 30 or to the polish head 110. If the firstvalve 236 is moved to its third position and the second valve 238 isopened, then pressurized air does not pass through the first valve 236.Instead, it goes through the second valve, through the venturi 240 toatmosphere 242. When pressurized air goes through the venturi 240, itcreates a vacuum, which pulls air from the end point.

The valves 114, 116, which control whether the suction feet 30 receivepressurized air or a vacuum, are controlled in part by the vacuumrelease button 66. When the operator presses that button 66, it causesthe first valve 236 to open, sending pressurized air to the feet. Thisprovides an air cushion which helps the operator slide the hanging unit20 along the side of the aircraft until it is properly aligned with thewindow. Then, the operator stops pushing the vacuum release button 66,and the central processor at the remote unit 16 shifts the valves 236and 238 to provide a vacuum at the feet 30.

The venturi valve 118, which controls whether the polish head blows outair to get rid of a polish pad or pulls a vacuum to pick up and hold apolish pad, is controlled by the central processor at the remote unit.

FIG. 14 is a schematic of the electrical control system, showing whatsignals the central processor 250 at the remote unit 16 receives andwhat it controls. It can be seen in this schematic that the centralprocessor 250 in the remote unit 16 has electrical connections with manydifferent parts of the machine 14. It receives a signal from the vacuumrelease button 66, which causes it to send signals to the venturi valves114, 116 for the suction feet 30. It receives a signal from the sensor192, which tells the central controller 250 whether there is a polishpad kit 190 in the receptacle 58, and, if there is not a polish pad kit190 present, the controller 250 will not allow the polish head 110 totravel along its path to polish the window.

The controller 250 sends signals to the strobe light 78 and to the soundalarm mounted on the remote unit 16 to let the operator know when thepolishing sequence is finished and to let the operator know if there isa problem with the machine. The controller receives signals from thestop/reset button 76 and from the start button 74 on the hanging unit20. The controller receives signals from the limit switches 80, 84, 88,and 92, which tell the controller that the polish head has reached theouter limits of operation. This is used to give the controller astarting point from which to operate, and it tells the controller ifsomething has gone wrong and the polish head has gone beyond where it issupposed to be. In the latter case, the controller 250 would stop themachine and sound the alarm and turn on the strobe light 78.

The controller 250 communicates with the X and Y step motors 54 and 38,giving them precise instructions to move the polish head support block56 along a plane substantially parallel to the surface of the aircraft.

The controller 250 communicates with the on/off switch 216 on the remoteunit 16, with the emergency stop button on the remote unit, and with thefan on the remote unit which cools the controller 250.

The central processor 250 controls the solenoid valve 232 which providespressurized air to move the polish head up and down. It also controlsthe solenoid valve 230 which provides pressurized air to operate the airmotor which causes the polish head 110 to rotate.

The central processor 250 communicates with a pressure switch 228, whichtells the processor 250 when the air pressure is low, and this causesthe central processor 250 to stop the machine and sound the alarm andlight up the strobe 78. If there is a signal to the central processor250 from the pressure switch 228 indicating a problem, the centralprocessor will signal the valves 234 and 234A-C, which will close inorder to maintain a vacuum in the suction feet 30.

The central processor turns the water pump on and off to provide waterfrom the tank 214 to squirt on the window. There is also a sensor in thewater tank 214, which tells the central processor 250 when the waterlevel is low, and the central processor 250 again signals the operatorthat the water supply must be replenished.

The central processor 250 also sends signals to the venturi valves 114,116, and 118 to control the air flow to the vacuum feet 30 and to thepolish head 110.

Normal operation of the machine is as follows:

The remote portion 16 and the hanging portion 20 of the machine 14 arerolled out to the aircraft 10 on dollies. The remote unit 16 isconnected to a power source and to a pressurized air source. Theoperator turns on the main on/off switch 216 on the remote unit 16. Thecentral processor 250 signals the step motors 38, 54 to lock, so theywill not move. Then the operator looks at the display through the window210 and pushes the buttons 212 to select the type of aircraft window tobe polished. For example, the operator will select "Boeing 747" and thenpress "enter".

The computer signals the valves 114, 116, 118 and 232 to create asuction in the suction feet 30, to create a suction in the polish head110, and to retract the polish head 110. The vacuum release light in thevacuum release button 66 comes on.

Then, the operator pushes the vacuum release button 66, which switchesthe venturi valves 114, 116, 118 to pressure, and picks up the hangingunit 20 by the handles 64. Then, the operator lifts the hanging unit 20up to the side of the aircraft 10, placing the hanging unit 20 on top ofa window 12, and uses the window locating brackets 62 to properly alignthe hanging unit 20 with the window 12. The operator continues to pushthe vacuum release button 66 while aligning the unit 20 with the window12, as this provides a cushion of air through the feet 30, which helpsthe hanging unit 20 slide over the surface of the aircraft. Once thehanging unit 20 is properly aligned with the window 12, the operatorreleases the button 66, causing a vacuum to be pulled through thesuction feet 30, thereby causing the hanging unit 20 to adhere to theaircraft 10 due to the suction in the feet 30. As was explained earlier,there are two venturi valves 114, 116 which control the suction to thefeet, and the unit 20 will hang on the aircraft even if only one of thefeet 30 has suction.

The operator opens a polish pad kit 190 and places the open kit 190 inthe receptacle 58. With the hanging unit 20 mounted on top of the window12, the operator then pushes the start button 74, which signals thecentral processor 250 to start the operating sequence. The processor 250then tells the step motors 38, 54 to drive the polish head carrier blockto the left rear corner of the frame 24. The third limit switch 88 tellsthe processor 250 when it reaches the contact 90, indicating it hasmoved all the way to the left, and the second limit switch 84 tells theprocessor 250 when it reaches the contact 86, indicating it has movedall the way to the rear of the frame 24. The processor 250 designatesthis position as the "zero" position.

The processor 250 then signals the step motors 38, 54 to move the polishhead support block 56 to a point directly over the polish pad kit 190,and it signals the valve 232 to lower the polish head. It also signalsthe venturi valve 118 to switch to a vacuum, so the uppermost polish pad196 (the finishing pad impregnated with a fine-grain finishing compound)is sucked onto the polish head 110.

The processor 250 then signals the valve 232 to retract the polish head,and it signals the step motors 38, 54 to move the polish head carrierblock 56 directly over the second receptacle 60. The processor 250 thensignals the valve 232 to extend the polish head, and it signals theventuri 118 to blow air out the polish head 110, depositing the upperpad 196 into the second receptacle 60.

The processor 250 then sends the polish head 110 over to the kit 190 topick up the second polish pad 198, which is impregnated with acoarser-grain polishing compound. Then, the processor 250 directs thestep motors 38, 54 to move the polish head carrier block 56 over thecenter of the window. The processor turns on the water pump or opens avalve in the water line, which sends water from the tank 214 through thewater line 96 to the water nozzle 70 to squirt on the window. Theprocessor directs the motors 38, 54 to move the polish head supportblock 56 down the middle of the window to the bottom of the window,while water is squirting out the nozzle 70 to wet the window.

Then, the central processor vents the cylinder valve 232 to atmosphere,venting the lower chamber of the cylinder in order to extend the polishhead 110 to the window, and opens the air motor valve 230 to turn on theair motor, causing the polish head to rotate. The central processor 250then directs the motors 38, 54 to drive the polish head along apredetermined path in order to cover the entire window, and periodicallysquirts water on the window as the polishing process proceeds.

Once the pad 198, which was impregnated with a polishing compound, hascompleted its path, the processor 250 retracts the polish head, placesthe polish head over the kit 190, and causes air to blow out the polishhead 110 to deposit the used pad 198 in the kit 190.

Then, the polish head goes over to the second receptacle 60 and picks upthe other pad 196, which has been impregnated with a fine-grainfinishing compound. The sequence is repeated, with water squirting andthe polish head rotating as it travels a predetermined path over thewindow. Again, the used polish pad is deposited into the kit 190.

Then, the polish head is retracted, and the motor 38 moves the polishhead 110 forward a bit. The central processor 250 then turns on thealarm and the strobe 78 and the display in the window of the remote unit16 says "program finished". This signals the operator that it is time tomove the hanging unit 20 to the next window.

The operator presses the stop button 76, pushes down the vacuum releasebutton 66, and moves the hanging unit 20 to the next window. Then theoperator removes the used polish pad kit 190 from the machine, and opensand installs a new polish pad kit 190. Then the operator pushes thestart button 74, and the process repeats.

In this manner, it is possible for a single operator to operate severalmachines at once in order to quickly polish all the windows of theaircraft.

It will be obvious to those skilled in the art that modifications may bemade to the embodiment of the invention described above withoutdeparting from the scope of the present invention.

What is claimed is:
 1. A machine for automatically polishing aircraftwindows, comprising:a polish head mounting block defining a verticaldirection; a polish head shaft mounted on said polish head mountingblock, said polish head shaft having a hollow interior and an upper endand a lower end; a motor which rotates said polish head shaft relativeto said polish head mounting block; a flexible drive joint mounted atthe lower end of said polish head shaft; a polish head mounted on saidflexible drive joint so that said polish head is rotationally driven bysaid polish head shaft and can pivot relative to said shaft; saidflexible drive joint having a hollow interior which communicates withthe hollow interior of said polish head shaft; and said polish headbeing permeable, so that pressurized air passing through the hollowinterior of said polish head shaft passes through said flexible drivejoint and through said permeable polish head, and so that, if a vacuumis drawn on the interior of said polish head shaft, it pulls a suctionthrough said polish head and through said flexible drive joint.
 2. Amachine as recited in claim 1, and further comprising a piston andcylinder arrangement mounted on said polish head mounting block; whereinsaid polish head shaft is mounted so as to move up and down relative tosaid polish head mounting block as said piston moves relative to saidcylinder.
 3. A machine as recited in claim 2, and further comprising apolish pad held on said polish head by a suction drawn through saidpolish head drive shaft, said polish pad having approximately the samediameter as said polish head.
 4. A machine as recited in claim 3,wherein said polish pad is impregnated with a polishing compound whichdissolves in water.
 5. A machine as recited in claim 1, and furthercomprising a spray nozzle mounted on said polish head support block forspraying water onto the aircraft window to be polished by the polishhead.
 6. A machine as recited in claim 1, and further comprising aspring between said piston cylinder arrangement and said polish head,for providing a spring force to press said polish head against theaircraft window.
 7. A machine as recited in claim 1, and furthercomprising a frame including suction feet for mounting on the side ofthe aircraft, wherein said polish head mounting block is mounted on saidframe for movement along two axes of a plane substantially parallel tothe surface of the aircraft.
 8. A method of cleaning aircraft windows,comprising the steps of:mounting the frame of a polishing machine,having a polish head, on the aircraft on top of a window; providingpressurized air, water, and electricity to said polishing machine andturning on the machine; mounting a kit including a plurality of polishpads on said frame; directing the polish head of the machine to go tothe kit, and using the pressurized air to provide a vacuum to the polishhead, using that vacuum at the polish head to pick up the polish pad;directing the machine to squirt water and to rotate the polish head asthe polish head follows a predetermined path along the window to polishthe window; and directing the machine to provide pressurized air to thepolish head to eject the polish pad after the predetermined path hasbeen completed.
 9. A polishing machine for polishing aircraft windows,comprising:a frame defining upward, downward, forward, rear, left andright directions; a plurality of suction feet mounted to said frame anddirected downwardly; a polish head mounted on said frame and directeddownwardly; a first pressurized gas line connected to said polishingmachine, through which pressurized gas is supplied to said polishingmachine, said first pressurized gas line including conduits to saidsuction feet; a first venturi valve in fluid communication with saidfirst pressurized gas line, wherein, when said first venturi valve is ina first position, it provides pressurized air to said suction feet, and,when said first venturi valve is in a second position, it uses thepressurized air to create a suction at said suction feet.
 10. A machineas recited in claim 9, and further comprising:a handle for holding saidmachine when it is being aligned with an aircraft window; and a controlmounted near said handle for controlling said first venturi valve.
 11. Amachine as recited in claim 10, and further comprising a cover for saidcontrol in order to prevent anyone from accidentally changing theposition of said first venturi valve when said machine is operating. 12.A machine as recited in claim 9, and further comprising a secondpressurized gas line, which is in fluid communication with said polishhead; and a second venturi valve in fluid communication with said secondpressurized gas line, wherein, when said second venturi valve is in afirst position, it provides pressurized gas to said polish head to blowa polish pad away from said polish head, and, when said second venturivalve is in a second position, it creates a vacuum at said polish head,to hold a polish pad on said polish head.
 13. A machine as recited inclaim 12, and further comprising:a first receptacle mounted on saidframe for receiving a polish pad kit; and a sensor on said firstreceptacle which senses whether there is a polish pad kit in said firstreceptacle.
 14. A machine as recited in claim 13, and furthercomprising:a polish pad kit in said first receptacle, said polish padkit including a substantially cup-shaped holder and a plurality ofpolish pads in said cup-shaped holder, each of said polish padsincluding a circular backing plate and a plurality of polish materialsegments adhered to said circular backing plate, said segments beingspaced from each other to permit liquid and air to pass between saidsegments.
 15. A machine as recited in claim 14, wherein the polishmaterial segments on at least one of said polish pads are impregnatedwith dry polishing compound so that, when the impregnated polish padcomes into contact with water, the polishing compound is dissolved bythe water, releasing the polishing compound from the impregnated polishpad.
 16. A machine as recited in claim 14, wherein said cup-shapedholder includes a plurality of projections and said first receptacleincludes a plurality of slots which receive said respective projections,wherein said cup-shaped holder is releasably mounted on said firstreceptacle by pushing the projections down, into their respective slotsand rotating the cup-shaped holder relative to the receptacle.
 17. Amachine as recited in claim 13, and further comprising a secondreceptacle mounted on said frame, wherein said second receptacle isadapted to receive polish pads which have been removed from said firstreceptacle.
 18. A polishing machine for polishing aircraft windows,comprising:a frame defining upward, downward, forward, rear, left andright directions; a plurality of suction feet mounted on said frame anddirected downwardly; a polish head mounted on said frame and directeddownwardly; a first pressurized gas line connected to said polishingmachine, whereby pressurized gas may be supplied to said polishingmachine, said first pressurized gas line including conduits to saidsuction feet; a second pressurized gas line connected to said polishingmachine, said second pressurized gas line in fluid communication withsaid polish head; a first venturi valve in fluid communication with saidfirst pressurized gas line, wherein, when said first venturi valve is ina first position, it provides pressurized air to said suction feet, and,when said first venturi valve is in a second position, it uses thepressurized air to create a suction at said suction feet; a secondventuri valve in fluid communication with said second pressurized gasline, wherein, when said second venturi valve is in a first position, itprovides pressurized gas to blow a polish pad away from said polishhead, and, when said second venturi valve is in a second position, itcreates a vacuum at said suction head for holding a polish pad on saidpolish head; a first step motor mounted on said frame for providing theforward-to-rearward motion of said polish head; a second step motormounted on said frame for providing the left-to-right motion of saidpolish head; an air-operated motor mounted on said frame, saidair-operated motor being mounted to rotate said polish head whenpressurized air is provided to the air-operated motor; and apiston-cylinder combination mounted on said frame to raise and lowersaid polish head.
 19. A machine as recited in claim 18, and furthercomprising a plurality of solenoid valves which control the flow of airto said air-operated motor and to said piston-cylinder combination;wherein said venturi valves are also solenoid valves; and an electricalcontrol system which controls said solenoid valves and said step motorsso that said polish head automatically picks up a polish pad, moves downto the surface of a window, rotates as it moves along a predeterminedpath to polish the window, and then ejects the polish pad.
 20. A machineas recited in claim 19, and further comprising a central controller insaid electrical control system, which is programmed with predeterminedpaths for polishing the windows of a plurality of different types ofaircraft; and a selector switch on said machine for communicating withsaid central controller to select the type of aircraft window to bepolished.